2. The name Yangguan originated in the Han Dynasty, and Guansai was located in the northwest of China. This place was named Yangguan because it was in the south of Yumenguan.
3. China emphasized geomantic omen in ancient times. On this basis, a variety of statements have been formed. After a long time, everyone agrees that the south of the mountain is sunny and the north of the water is cloudy. Because it is in the south of Yumenguan, it is called Yangguan. Yangguan and Yumenguan are both important passes for the Han Dynasty to the Western Regions.